1. Field of the Invention
The present invention relates to a shielding device for a printed circuit board, and particularly to a shielding device having a shielding enclosure that may be easily removed.
2. Discussion of the Related Art
Electronic components of a printed circuit board radiate electromagnetic waves which generate noise or unwanted signals. Accordingly, it is highly desirable to provide shielding for electronic components of printed circuit boards, which is susceptible to electromagnetic radiation. Since the electric telecommunication equipment must withstand interference of electromagnetic radiation, shielding device must be used therein in order to decrease radiation emission.
The shielding device usually contain an enclosure and a frame. The cover of the shielding device can be opened to access of the electronic components inside the enclosure. Referring to FIGS. 8 and 9, a conventional shielding device includes a frame 10 and a shielding enclosure 30. The frame 10 is mounted on a printed circuit board 20, and is used for surrounding electronic components on the printed circuit board 20. The frame 10 is made up of a plurality of walls. Each wall positions a plurality of projections 12. The shielding enclosure 30 includes a cover 32 and a plurality of flanges 34. The shape of the cover 32 is similar to that of the frame 10. Each flange 34 forms a fixing piece 36, which includes a body portion 362 and a tab 364. The body portion 362 is perpendicularly connected to the cover 32, and is spaced from a bottom surface of the flanges 34. The body portion 362 defines a through hole 3622 for receiving a corresponding projection 12. The tab 364 is perpendicularly extended from the body portion 362. The tab 364 is spaced from the bottom surface of the flanges 34, thereby defining a clearance.
In assembly, each projection 12 is received in a corresponding through hole 3622 for securely attaching the shield enclosure 30 to the frame 10. During removal of the shield enclosure 30, a suitable tool is inserted into the clearance under the tab 364. Then, the tool is used to raise the fixing piece 36 away from the frame 10. Accordingly, the projection 12 is separated from the through hole 3262, thereby the shield enclosure 30 being removed from the frame 10. Since the opening direction of the clearance is parallel with the cover, the tool needs to be substantially horizontally inserted into the clearance under the tab 364. Accordingly, the printed circuit board needs to preserve an extra space for the tool to be received therein. When a plurality of shielding devices are positioned adjacent to each other or the electronic component on the printed circuit board 20 is close to the fixing piece 36 of the shielding enclosure 30, the tool is difficult to be inserted into the clearance. Therefore, this makes it difficult to remove the shielding enclosure 30.
Therefore, an improved shielding device is desired in order to overcome the above-described shortcoming.